PROJECT SUMMARY The development and progression of heart failure (HF) involves many processes that occur after cardiac stress or injury. Compensatory neuro-hormonal activation and chronic stimulation of the sympathetic nervous system (SNS) is accompanied by the pathological increase in G protein-coupled receptor kinase (GRK) 2 expression. Research indicates that elevated GRK2 levels are central to the progression of HF and are instrumental in b1- adrenergic receptor (b1AR) desensitization and downregulation, cardiomyocyte apoptosis, and cardiac dysfunction. GRK2 inhibition has proven to be a powerful tool to rescue these dysfunctions. However, the cause of GRK2?s transcriptional upregulation in the heart is still largely unknown. As miRNAs are involved with post- transcriptional regulation of GRK2 in other tissues, this project aims to determine if GRK2 is regulated in a similar manner in the heart for the long-term goal of developing the miRNA into a miRNA replacement therapy. The project?s short-term goal is to develop a comprehensive understanding of the relationship between miRNAs and GRK2 in health and HF. Our hypothesis states that GRK2 is post-transcriptionally regulated by a miRNA and this regulation is altered in HF. The proposal is divided into two aims. Aim 1 investigates the mechanism of which miR-181c-5p is able to decrease GRK2 protein and RNA levels. Aim 1 includes various methods such as miRNA stability/decay assays, translational analysis, and miRNA transfections. Aim 2 is concerned with determining if there is any therapeutic application for miRNA-181c in HF. Aim 2 employs a mouse model of HF in addition to tissue sectioning, mouse surgical techniques, organ harvesting, and other molecular techniques in Aim 1. Discovering a regulator of GRK2 would provide the field with a new method of GRK2 inhibition as well as a mechanism of GRK2 upregulation. The use of miRNAs as pharmacological agents is a growing field as miRNAs have several advantages over existing therapies including their small size and stability. GRK2 inhibition through miRNA therapy has the potential to be an effective and powerful method of preserving cardiac physiology long- term, improving overall mortality, and ultimately enhance the health and quality of individuals inflicted with HF. The project described, along with the proposed training plan is designed to promote the development of the trainee into being a successful independent scientist. Graduate coursework and candidacy exams have been completed. However, the trainee continues to receive training in scientific rigor, biomedical ethics, and laboratory safety/conduct. The project involves molecular biology and its related techniques within a cardiovascular setting. Therefore, the training plan will educate and broaden the knowledge that the trainee has in these research areas and scientific disciplines. It will provide her a strong basis to launch into a career studying gene regulation at the post-transcriptional level. It also includes career development activities such as writing, public speaking, and networking. !